Link to video:
https://www.youtube.com/watch?v=0mS10XYqhPA
I made a video of my M&P 15T trigger results, and the following video shows the results to my 15-22 trigger modifications. The parts I purchased were a set of JP light tension springs ($10), and a set screw to control trigger take-up ($.50 cents). The results of my modifications do not compare to the high dollar Geissele, Timney, or similar triggers, but it is much improved over the stock trigger pull. The rifle is safe, as the hammer will not slip off the sear, and the disconnector is timed properly. It has a very smooth pull and a crisp break at 2.5 pounds. I like a light trigger pull, but by changing springs it could be made to 5 pounds and higher. I have not had any lights hits, shooting a variety of ammunition.
Results:
1/8 inch of trigger movement, from at rest to full travel stop.
1/16 inch trigger take-up to break.
1/16 inch of trigger over-travel, after break
3/32 inch trigger movement to reset.
2 pounds 8 ounces of trigger pull weight.
This is what I did:
Polished the sear and hammer engagement surfaces.
Installed a 1/4 long 1/4X28 set screw in the hand grip bore, to adjust take-up.
Installed JP light springs.
Lightened the JP trigger spring tension, not the hammer spring.
Ground metal from the upper rear of the trigger base, so the safety lever would fit back in.
Filed the disconnector to correct timing.
Polished the disconnector and hammer engagement surfaces, so the trigger would reset with the light trigger spring.
Light coat of anti-seize on all the engagement surfaces.
Lots of assembly, disassembly, checking and testing.
Link to video:
https://www.youtube.com/watch?v=0mS10XYqhPA
Bob